Since Oculus Go is about to be launched (assuming release time frame outlined in 2017 as "beginning of 2018" still stands) I am wondering if UE 4.19 (or 4.20) will get more optimizations / features enabled or get Vulkan (or ES 3.1) support for Gear VR and Oculus Go.

"ES3.1 doesn't seem to be optimized at all and is deferred (ES2 is forward from what I've heard).On the mobile codepath, if you check in the ES3.1 box, you get the ES3.1 version of the mobile forward renderer. There is also the "ES3.1 mobile deferred" box which obviously is a deferred renderer that you shouldn't use."

I will be making a sticky note to advertise that developers should stick to forward on mobile.

Here is some information from our integrations team:"On the mobile codepath, if you check in the ES3.1 box, you get the ES3.1 version of the mobile forward renderer. There is also the "ES3.1 mobile deferred" box which obviously is a deferred renderer that you shouldn't use."

I see there is "Support Open GL ES deferred shading", but I never checked that box and I still get horrible performance when "Support Open GL ES3.1" is enabled. So I am not sure whether that box is related to ES2.0 or ES 3.1 is simply that bad in UE4 when it comes to mobile VR.

is there any update on oculus go ES3.1 performance? I'm in the process of migrating to UE4 4.21 from 4.20. On 4.20 when I repackage with the Support ES3.1 toggle on I get some pretty patchy performance. I have a steady 60 with no hitches on ES2, in 3.1 I get huge slow down. I don't know if this will be better in 4.21 but I'm currently looking into implementing World Position Offset vertex shader which isn't supported on ES2. I'm doing this for tree/ foliage movement which is a very nice visual enhancement. It's supposedly doable on ES3.1.

is there any update on oculus go ES3.1 performance? I'm in the process of migrating to UE4 4.21 from 4.20. On 4.20 when I repackage with the Support ES3.1 toggle on I get some pretty patchy performance. I have a steady 60 with no hitches on ES2, in 3.1 I get huge slow down. I don't know if this will be better in 4.21 but I'm currently looking into implementing World Position Offset vertex shader which isn't supported on ES2. I'm doing this for tree/ foliage movement which is a very nice visual enhancement. It's supposedly doable on ES3.1.

You can now use Emulated Uniform Buffers for projects that target the OpenGL ES3.1 feature level, significantly reducing memory usage and improving rendering performance
depending on your application complexity. Emulated Uniform Buffers have
also been optimized to help reduce the size of the data that needs to
be transferred to the GPU when your project is being packaged. To enable
Emulated Uniform Buffers when using the OpenGL ES3.1 feature level, add
the following line to your project's DefaultEngine.ini under
[/Script/Engine.RendererSettings]:

[/Script/Engine.RendererSettings]
OpenGL.UseEmulatedUBs=1

Epic said this was the major problem with 3.1 performance that they fixed for Fortnite:

Yes, they did. But improving GLES 3.1 for pancake isn't the same (at times) as improving it for VR.

That's true but in 4.21 at least there have been some mobileVR 3.1 improvements. (see: hardware culling now working for multiview). I am also sure that the Emulated Uniform Buffers works for mobileVR as well since it has nothing to do with stereo rendering.

Anyway even more excited about the next unreal version for mobileVR as Epic hopefully includes their improvements to get Roborecall working nicely on the Quest!